Leprosy might not have originated in India and spread to other parts of the world as has been believed for centuries.
A French genetics study comparing strains of leprosy-causing bacteria has revealed some surprises about how the pathogen evolved and how it spread across the continents by human migrations.
The findings of the study, led by scientists at the Pasteur Institute in Paris, and published in the May 13 issue of Science, indicate that the world's existing leprosy infections are all caused by a single bacterial clone that has spread yet barely mutated for centuries. The magazine is published by the American Association for the Advancement of Science, a non-profit body.
'They also show that the disease may have begun in East Africa, as opposed to India as previously thought, and then spread to the other continents in part through European colonialism and later the slave trade,' according to a release by the Pasteur Institute released Monday.
One of the oldest known human diseases, leprosy is still a significant problem in parts of the developing world, especially India. According to the World Health Organization, roughly 500,000 new cases were detected in 2003.
"Leprosy is still very real and devastating to patients who aren't treated appropriately. The better we can understand this pathogen's genome and the subtle differences among its various strains worldwide, the better position we'll be in to ultimately eliminate the disease," said Caroline Ash, senior editor of Science.
Stewart Cole, author of the Pasteur Institute study said that the ability to trace an infection back to a certain region may help public health workers monitor the movement of the disease over time and determine the geographic source of new infections.
Cole said that historically, it has been thought that leprosy originated in the Indian subcontinent and was then introduced to Europe by Greek soldiers returning from the Indian campaign of Alexander the Great.
"More research will be necessary to confirm this, but the new findings indicate that the disease actually originated in East Africa or perhaps the Near East, then migrated eastward and westward," he was quoted in the release.
According to the institute, the Europeans and North Africans then spread Leprosy to West Africa, and the slave trade brought the disease from West Africa to the Caribbean and South America. Europeans also introduced leprosy to North America.
"Colonialism was extremely bad for parts of the world in terms of human health," Cole said.
Cole and his international research team compared the genome of seven strains of M leprae taken from patients around the world and then grown in armadillos, an insect-eating mammal native to Central and South America, until the samples were large enough to analyze.
'It seems that there was only a single source of the bacterium that was at the origin of this global pandemic,' Cole said.